Overhead reduction in frequency hopping system for intermittent transmission

Abstract

A radio transmission telemetry system includes several transmitters intermittently transmitting short messages indicative associated sensors status and a receiver for collecting data from the sensors. Each transmitter changes time and frequency of transmissions according to a time-frequency pattern that is different for each transmitter. The receiver identifies each source of transmissions based on its unique variations of the transmission time and frequency, thus eliminating the necessity to include the transmitter ID code in each transmitted message. Thus, overhead in the transmissions is reduced. In addition, the sensor status and other supervisory information such as battery status are partitioned and included in the transmitted messages in portions and at different rates according to the state of the PN-generator for producing the time-frequency pattern. The receiver can determine what and when is included without additional control bits in the transmitted messages. Thus, overhead in the transmissions is further reduced.

1. A telemetry system comprising:
 a plurality of transmitters each of which, when operative, transmits independently of any other of said plurality of transmitters and independently of any equipment for receiving from any of said plurality of transmitters and at transmission frequency and time between transmissions controlled according to a time-frequency pattern that is different for each of said plurality of transmitters, and includes selectively, in transmissions, portions of information payload according to said time-frequency pattern; and 
 a receiver for: 
 (a) holding, simultaneously for each plurality of transmissions, data indicative of an expected time and an expected frequency of at least one future transmission, and 
 (b) identifying said portions of information payload based on said time-frequency pattern. 
 
   
   
     2. The telemetry system of  claim 1  wherein each of a plurality of transmissions is devoid of bits of a transmitter identification. 
   
   
     3. The telemetry system of  claim 1  wherein said receiver is enabled to identify at least one of said plurality of transmitters based on said time-frequency pattern. 
   
   
     4. The telemetry system of  claim 1  wherein said portions of information payload include bits of time-frequency pattern generator. 
   
   
     5. The telemetry system of  claim 1  wherein, said receiver is enabled to aggregate said portions of information payload. 
   
   
     6. The telemetry system of  claim 1  wherein said portions of information payload are included at various rates in transmitted messages. 
   
   
     7. The telemetry system of  claim 1  wherein said portions of information payload are included according to a variable algorithm. 
   
   
     8. A receiver comprising:
 logic for holding, simultaneously for each plurality of transmissions, data indicative of an expected time and an expected frequency of at least one future transmission, wherein each said plurality of transmissions is transmitted by different one of a plurality of transmitters, and wherein each of said plurality of transmitters, when operative, transmits independently of any other of said plurality of transmitters and independently of any equipment for receiving from any of said plurality of transmitters, and wherein, transmission frequency and time between transmissions are controlled according to a time-frequency pattern that is different for each of said plurality of transmitters; and 
 logic for identifying portions of information payload bits included in transmissions based on said time-frequency pattern. 
 
   
   
     9. The receiver of  claim 8  wherein said receiver further comprises logic for identifying at least one of said plurality of transmitters based on said time-frequency pattern. 
   
   
     10. The receiver of  claim 8  wherein said receiver is enabled to aggregate said portions of information payload bits. 
   
   
     11. A plurality of telemetry transmitters, each of which comprises:
 a circuit for transmitting intermittently, at various transmission frequencies, independently of any other of said plurality of transmitters, and independently of any apparatus for receiving from any of said plurality of transmitters, and 
 logic for controlling transmission frequency and time between transmissions according to a frequency-time pattern that is different for each of said plurality of transmitters, 
 wherein, in operation, each of a plurality of transmissions comprises a portion of information payload, wherein said portion is selected based on said frequency-time pattern. 
 
   
   
     12. The plurality of telemetry transmitters of  claim 11  wherein each of a plurality of transmissions is devoid of bits of a transmitter identification. 
   
   
     13. The plurality of telemetry transmitters of  claim 11  wherein said portion of information payload includes bits of time-frequency pattern generator. 
   
   
     14. The plurality of telemetry transmitters of  claim 11  wherein various portions of information payload are included at various rates in said transmissions. 
   
   
     15. The plurality of telemetry transmitters of  claim 11  wherein said portion of information payload is included according to a variable algorithm.